1. Field of the invention:
The present invention relates to an outboard engine, and more particularly to a power unit in an outboard engine.
2. Description of the Prior Art:
Outboard engines are frequently carried around and stored on land since are generally used in various kind of boats by being secured to such boats in the manner that they can be easily detached from the boats. It has been customary practice during transportation or storage to keep the outboard engine upright with the aid of a support or drain engine oil so that no engine oil will find its way into the engine cylinder and hence no engine trouble will be caused. Therefore, it has been troublesome to handle the outboard engine while it is being transported or stored.
It is desirable for easier handling that the outboard engine be as compact as possible. For protecting the engine from water, particularly sea water, it is necessary to surround the engine with an engine cover. If the engine cover were too small for the engine, intake air drawn into the engine would be affected by the heat generated by the engine, resulting in a lowered charging efficiency of the engine and a reduced engine power output.
The outboard engine is also required to separate sea water spray, dust, or other foreign matter from intake air so that the service life of the engine will not be impaired. Another requirement is that since the operator is positioned just in front of the engine during operation of the engine, noise produced when intake air is drawn into the engine be reduced to as low a level as possible to lessen the fatigue of the operator. However, it has proven that these requirements are contradictory to the demand for more compact outboard engines.